AC would be equivalent to 4. I know that the triangle is a 90, 45, 45 triangle which means 2 of the angles AND sides are equivalent to each other. Since angle B is 45 degrees angle C has to be 45 degrees. Same goes for the sides. Since AB=4, AC=4. It wouldn't be BC bc that's the hypotenuse or the longest part of the triangle. AC wouldn't be equal to 2 since it won't follow the rule of a 90, 45, 45 triangle. :|
